| Porcine pseudorabies virus belongs to the Alpherpesvirus subfamily of Herpesviridae family.It is a neurotropic virus that can cause acute infectious diseases in a variety of animals.With the emergence of this variant strain,classical vaccine strains are not effective in preventing pseudorabies caused by variant strains completely,which brought huge economic losses to the pig industry.Since the pseudorabies virus can be preserved for a long time after infecting the body,this poses a huge challenge for the prevention and control of pseudorabies.Therefore,understanding the origin,evolution,diversity and the difference of major glycoprotein gB,gC,gD and gE between mutant strains and traditional classical strains of PRV and development of novel antiviral drugs have great significance for controlling the disease.The main contents of this research were as following:1.Genomic characteristics and evolutionary analysis of PRV epidemic strains in Eastern ChinaSince late 2011,outbreaks of pseudorabies virus(PRV)have occurred in Southern China causing major economic losses to the pig industry.Here,we analyzed samples from intensive pig farms in East China between 2017 and 2019 and sequenced the main glycoproteins gB,gC,gD,and gE to study the evolution characteristic of PRV.Based on the gC gene,we found that PRVs belong to clade 2 and a founder effect along the PRV epidemic process.In addition,we detected inter-and intra-clade recombination and some specific amino acid changes and positive selected sites possibly associated with functional changes.For example,gB site 43 is in proximity with B-cell epitopes 59 to 126,site 75 on gC is associated with virus adsorption,and site 194 is on the 1/3 N terminal of the gC protein,which is associated with the HS receptor-binding domain.In addition,the amino acid sites in which we found changes in relation.2.Study on antiviral activity of germacroneThe development of new anti-pseudorabies virus drugs is of great significance for the treatment and prevention of pseudorabies.Therefore,we studied the effect of germacrone on the inhibition of pseudorabies virus,and further investigated its antiviral mechanism.We found that germacrone can inhibit PRV replication in a dose-dependent manner by Western blot and IFA.In order to investigate the period in which germacrone is active during PRV infection,we treated the drug at different time points of infection and found that germacrone plays a role in the early stage of viral replication.We investigated the mechanism by which germacrone inhibits the replication of PRV and found that germacrone does not directly kill the virus or block the invasion of virus,nor does it affect the expression of the PRV receptor protein Nectin-1.3.Germacrone’s inhibition of autophagy and apoptosis induced by pseudorabies virus and the mechanism of germacrone on antiviral activityAutophagy is a mechanism for self-protection with environmental stress.It has great significance for resisting adverse environment and improving cell survival.In this study,we found that PRV can induce apoptosis and autophagy in cells,and germacrone can inhibit the apoptosis and autophagy produced by the virus.Besides,by investigating the relationship of autophagy,PRV and germacrone,we found that autophagy can inhibit the replication of PRV,while germacrone can induce autophagy,indicating that germacrone may inhibit PRV replication by causing autophagy. |
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